1. Field of the Invention
This invention relates to dispensers and more particularly to a chemical product venturi eductor device for selectively dispensing and mixing two fluids at a dilution ratio and a selected total fluid flow rate.
2. Prior Art
Custodial staff store cleaning supplies in a custodial closet. For example, chemical fluids such as cleaning solutions are typically stored in concentrated form in a disposable container. The custodial worker mixes the concentrated cleaning solution with water in a spray bottle or mop bucket to the desired strength (i.e., dilution ratio).
Pouring the concentrated cleaning solution directly from the disposable container into the end use container (e.g., spray bottle, mop bucket) creates problems. For example, human error results in an incorrect dilution ratio. An overly dilute cleaning solution does not clean and sanitize as desired. An overly concentrated cleaning solution may waste cleaning solution or damage property.
Consequently, dispensers are known for controlling the dispensing of cleaning solutions at a desired dilution ratio. Moreover, these known dispensers will fill at a flow rate appropriate to the size of the end use container. For instance, about one gallon per minute flow rate is appropriate for a spray bottle whereas about three or four gallons per minute is appropriate for a mop bucket.
These known dual flow rate dispensers use a gravity feed system in which the disposable container of concentrated cleaning solution is inverted. When the user selects one of the two flow rates, concentrated cleaning solution is allowed to pass through an orifice into a mixing chamber. In one system, the action of turning the disposable container mechanically turns on the water and opens the orifice to allow the mixing. In another system, the user turns on water pressure and the water pressure activates a plunger mechanism to open the orifice.
These gravity feed systems have a number of shortcomings. For example, the disposable container is inverted, and thus tends to leak if not properly installed or if the gravity feed system fails to seal properly. As another example, the dilution ratio is adversely affected by water pressure. Typical water pressure often varies from 20-80 pounds per square (psi), with low pressure 20-30 common in certain countries or remote facilities. As the water pressure varies, the dilution ratio varies, since the amount of concentrated cleaning solution that is mixed is based on gravity and the size of the orifice. The low pressure is particularly difficult for mechanism designed to open the orifice at a higher water pressure, causing even more dilute mixtures if the mechanism fails to open fully or quickly. As yet a further example, the mechanisms for opening the orifice, either by mechanical twisting or activating water pressure, are more complicated than desired for reliable operation and ease of manufacturing. As yet an additional example, the same dispenser is often used to dispense different types of chemical fluids. Thus, residual chemical fluid from previous dispensing typically has to be rinsed from the gravity feed system. This additional step is inconvenient and presents an opportunity for human error.
Consequently, a significant need exists for a dual flow dispenser that achieves a consistent dilution ratio across a range of water pressures and that does not tend to leak concentrated cleaning solutions.
In accordance with principles of the present invention, this need is met by eductively drawing a chemical fluid such as concentrated cleaning solution from an upright container, avoiding leaking by having unused chemical fluid return to the container. Moreover, the suction created by a venturi of an eductor varies with the water pressure. Consequently, the dilution ratio of an eductive dispenser varies less with water pressure than a gravity feed system. Thereby, an optimum dilution ratio is achieved, avoiding an ineffective, overly dilute mixture and avoiding a wasteful overly concentrated mixture. A preferred embodiment of the invention includes a system having an upright reservoir serviced by eductively drawn dual concentrate pickup tubes, facilitating differential rate dispensing that is more consistent than prior gravity fed systems, and with purge accumulators retrieving all unused chemical fluid in delivery passages of the dispenser back to the reservoir, thus preventing chemical carryover or contamination between dispensing applications.
Consistent with one aspect of the invention, a method provides mixing in an eductor a chemical fluid stored in a reservoir with a motive fluid by drawing the chemical fluid being drawn through a conduit from the reservoir into a venturi of the eductor. A pickup tube is contained in the chemical reservoir and includes an integral purge accumulator. Thus, when motive fluid is directed to the eductor, a suction is created at the venturi of the eductor. In response to the suction at the venturi, the chemical fluid is drawn from the reservoir via the pickup tube and conduit, thereby resiliently collapsing the purge accumulator. When the motive fluid is terminated, the conduit is simultaneously vented near the venturi, thereby allowing the purge accumulator to resiliently expand to withdraw chemical fluid from the conduit back into the environment of the reservoir. Consequently, another reservoir having another type of chemical fluid may be inserted without leaving residual chemical fluid in the dispenser.
Consistent with another aspect of the invention, a detachable reservoir is configured for a dispenser that eductively dilutes and dispenses a chemical fluid at two flow rates. The reservoir includes two pickup tubes that communicate between an opening of a bottle and a lower portion of the bottle. By having two pickup tubes, portions of the eductive dilution dispenser may be duplicated so that a specific dilution ratio and two total flow rates may be imposed for each path beginning at each pickup tube.
Consistent with an additional aspect of the invention, a dispenser dispenses at a consistent dilution ratio and at two flow rates by having dual eductors, each eductively drawing the chemical fluid from the reservoir through a respective pair of a conduit and a pickup tube. A control selectively directs motive fluid to the first and second eductors to dispense. The control also selectively blocks motive fluid to the first and second eductors while venting the corresponding conduit to facilitate withdrawing chemical fluid from the conduit without withdrawing mixed fluids from the eductor.
The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof.